How to Unflood a Chainsaw? A Guide to Fixing a Flooded Engine

how to unflood a chainsaw

Have you ever tried starting your chainsaw only to have it sputter and die? This is likely due to a flooded engine, a common issue caused by having too much fuel in the combustion chamber. While a flooded chainsaw can be frustrating, the good news is that it’s usually an easy fix. With some basic troubleshooting and maintenance, you can get your chainsaw up and running again quickly.

In this comprehensive guide, we’ll outline the steps to unflood a chainsaw so you can get back to cutting and trimming. We’ll cover what causes flooding, how to fix a flooded chainsaw, tips for prevention, and answers to frequently asked questions. With the help of top-ranking websites, you’ll have all the information needed to properly maintain your chainsaw and handle flooding issues.

What Causes a Chainsaw to Flood?

how to unflood a chainsaw

Before we dig into how to unflood a chainsaw, it helps to understand what causes the engine flooding in the first place. There are three main culprits that can lead to a flooded spark plug and combustion chamber:

Incorrect Fuel Mixture

One of the most common causes of chainsaw flooding is an improper fuel mixture. Chainsaws require a specific ratio of gas to oil, usually around 50:1. If you use too much oil in the fuel mixture, that excess can clog the carburetor and cause flooding issues. Always double check that you have the right gas-to-oil ratio before filling up your chainsaw.

See also  The Benefits of Using a Chainsaw with a Heated Handle

Clogged Air Filter

A critical maintenance task that can help prevent flooding is cleaning or replacing the air filter regularly. If the filter becomes clogged with sawdust, dirt, and other debris, it restricts proper airflow into the carburetor. This disruption in air flow causes an imbalance in the fuel system, allowing excess gas to build up and flood the engine.

Incorrect Starting Sequence

Flooding can also occur if the proper starting steps aren’t followed. If the choke is left on while pulling the starter cord, additional fuel is drawn into the engine which can easily cause flooding. Be sure to follow the manufacturer’s recommended sequence for starting the chainsaw to avoid drawing in excess fuel.

How to Unflood a Chainsaw?

If your chainsaw won’t start and you suspect it’s flooded, don’t panic. There are several straightforward steps you can take to unflood the engine and get it running again:

Letting the Chainsaw Sit

An initial step is to simply let the flooded chainsaw sit for 15-20 minutes. This allows time for any excess fuel in the combustion chamber to evaporate, making it easier to clear out the remaining gas and start the engine. As you wait, recheck the spark plug and air filter to address any visible issues.

Removing and Drying the Spark Plug

After letting it sit, the next step is to remove the spark plug completely using a spark plug wrench. Check for fouling or fuel saturation on the plug. If needed, use a wire brush or rag to fully dry the spark plug electrodes. This helps eliminate any excess fuel left over in the combustion chamber.

Purging the Engine’s Cylinder

With the spark plug still removed, pull the starter cord several times to help clear flooded fuel from the cylinder. This essentially purges and expels excess gas from the engine so it’s ready to start with a dry spark plug reinstalled. Make sure the choke is off so you don’t draw in more fuel while pulling the cord.

How to Unflood a Chainsaw? A Guide to Fixing a Flooded Engine

Preventing Chainsaw Flooding

While it’s good to know how to unflood a flooded chainsaw, prevention is even better. Here are tips to avoid engine flooding issues:

Proper Fuel Mixture

As mentioned before, the most common cause of flooding is an improper gas-to-oil ratio. Always double check the manufacturer’s specified fuel ratio and measure carefully when mixing gas and oil.

See also  How Chainsaws Aid in Agricultural Tasks: A Guide

Regular Air Filter Maintenance

Replace or clean the air filter regularly to prevent debris buildup that can restrict airflow and lead to flooding. Some filters can be cleaned by blowing them out while others need to be replaced completely. Refer to your owner’s manual for the recommended service interval.

Following the Correct Starting Sequence

Flooding is often caused by having the choke on while pulling the starter cord to turn over the engine. Get in the habit of following the proper starting procedure each time, allowing the choke to reset between pulls. Taking this care prevents drawing in excess fuel.

How to Start a Flooded Chainsaw?

If you’ve tried the steps to unflood your chainsaw, but it still won’t start, you may need some additional starting tips depending on the model:

Starting a Flooded Stihl Chainsaw

For Stihl chain saws specifically, follow these flooded engine starting steps:

  1. Let the chainsaw sit for 20 minutes to allow fuel to evaporate.
  2. Remove the spark plug and air filter. Dry both thoroughly if wet with fuel.
  3. Pull the starter cord several times with the spark plug still removed.
  4. Reinstall the dried spark plug and air filter.
  5. Engage the choke halfway and pull the cord.
  6. Push the choke back in once the engine tries to start.
  7. Pull the cord repeatedly until the engine starts.

Starting a Flooded Chainsaw with a Carburetor

On saws with a standard carburetor, use this sequence to start a flooded engine:

  1. Let the saw sit for 15 minutes, then remove the air filter and spark plug.
  2. Dry the spark plug electrodes. Pull the starter cord 5-6 times with the plug out.
  3. Replace the plug and air filter. Leave the choke off.
  4. Hold the throttle fully open. Pull the cord until the engine starts.

Troubleshooting a Flooded Chainsaw

If your chainsaw still won’t start after trying to unflood it, there could be another issue at play. Here’s how to troubleshoot:

Checking for Other Issues

A flooded engine may sometimes be caused by other issues like bad fuel or a faulty spark plug. Check that you have fresh gas in the tank, and inspect the spark plug for signs of wear. Replace components as needed.

See also  What Weight Is Chainsaw Bar Oil? A Guide

Seeking Professional Help

In some cases, flooding may indicate a bigger problem, like a failing carburetor. If your chainsaw continues to flood despite your best efforts, seek assistance from a small engine repair professional.


While a flooded chainsaw can certainly be annoying to deal with, unflooding the engine is straightforward if you follow the proper steps. Letting the saw sit, drying the spark plug, and purging the cylinder can usually get a flooded saw back up and running.

Prevention is also key – be diligent about proper fuel mixture, air filter service, and following the correct starting procedure. And don’t hesitate to consult a shop if you need a hand. With this guide, you have all the information needed to successfully deal with a flooded chainsaw. Just focus on each outlined step, and your saw will be back to cutting in no time!

Frequently Asked Questions

How long does it take for a flooded chainsaw to start?

After following the unflooding steps, a flooded chainsaw typically will start within several pulls of the starter cord. Allow 15-20 minutes initially for the fuel to evaporate before attempting to start the saw.

Can a flooded chainsaw be damaged permanently?

Flooding itself rarely causes permanent damage. However, trying to start a badly flooded saw for long periods can potentially damage the spark plug or cylinder. Follow the outlined steps to correctly unflood the engine.

How do I know if my chainsaw is flooded?

Common signs of a flooded chainsaw include the engine not starting, excess smoke, a fouled spark plug, and the smell of unburned gas fumes. The saw may also sputter or stall shortly after starting.

What is the correct oil-to-petrol ratio for my chainsaw?

Most chainsaws need a petrol to oil ratio around 50:1, but always check your owner’s manual. Stihl saws, for example, recommend a 50:1 mixture. Too much oil can quickly lead to fouling and engine flooding.

How often should I clean or replace my chainsaw’s air filter?

The air filter should be cleaned every 5-10 hours of use, more often if working in very dusty conditions. It’s recommended to replace the filter completely every 50 hours or after 6 cleanings.

Can I use a different starting sequence for my chainsaw?

It’s best to always follow the manufacturer’s recommendations for starting to avoid engine flooding. Deviating from the proper choke settings and starting steps can easily cause issues.

Is it safe to try starting a flooded chainsaw multiple times?

You can pull the starter cord several times when trying to start a flooded saw. But don’t crank continuously for more than 10 seconds to avoid potential engine damage. Give the saw a break to cool down between starting attempts.

Similar Posts